The relative contribution of orbital forcing and greenhouse gases to the North American deglaciation

Lauren J Gregoire, Paul J Valdes, A J Payne

Research output: Contribution to journalArticle (Academic Journal)peer-review

16 Citations (Scopus)
315 Downloads (Pure)

Abstract

Understanding what drove Northern Hemisphere ice sheet melt during the last deglaciation (21–7 ka) can help constrain how sensitive contemporary ice sheets are to greenhouse gas (GHGs) changes. The roles of orbital forcing and GHGs in the deglaciation have previously been modeled but not yet quantified. Here for the first time we calculate the relative effect of these forcings on the North American deglaciation by driving a dynamical ice sheet model (GLIMMER-CISM) with a set of unaccelerated transient deglacial simulations with a full primitive equation-based ocean-atmosphere general circulation model (FAMOUS). We find that by 9 ka, orbital forcing has caused 50% of the deglaciation, GHG 30%, and the interaction between the two 20%. Orbital forcing starts affecting the ice volume at 19 ka, 2000 years before CO2 starts increasing in our experiments, a delay which partly controls their relative effect.
Original languageEnglish
Pages (from-to)9970-9979
Number of pages10
JournalGeophysical Research Letters
Volume42
Issue number22
Early online date19 Nov 2015
DOIs
Publication statusPublished - 28 Nov 2015

Keywords

  • Ice sheets
  • Modeling
  • Milankovitch theory
  • Greenhouse gases
  • Insolation forcing
  • deglaciation
  • ice sheets
  • North America
  • orbit
  • greenhouse gases
  • Milankovic

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